This invention relates to speckled toothpastes containing agglomerated pigment particles. More specifically this invention relates to toothpastes colored in a speckled fashion with agglomerates of water-insoluble non-toxic pigment particles and a process for preparing said agglomerates.
Color has been acknowledged to play an important role in consumer acceptance of many products. In many cases color has been used to distinguish particular products in the market place and to identify products having particular distinct properties. Colored products are usually formulated by merely adding the desired dye to the other components prior to the mixing stage of the process. As the dyes currently utilized in toothpaste are all water-soluble, and varying large amounts of water are present in toothpaste, the desired color spreads and uniformly colors the entire product. An alternative means of uniformly coloring a toothpaste is to disperse uniformly in the paste very small particles of insoluble colored material which acts as a pigment. Although this material is discerned as discrete colored particles when the paste is examined under a magnifying lens, to the naked eye the paste has a uniform colored appearance. For example, colored thermosetting crosslinked resin particles can be used for uniform pigmentation of toothpastes as is disclosed in the U.S. patent application of R. A. Shaffer, Ser. No. 165,585, filed June 23, 1971, which is a continuation of Ser. No. 837,358, filed June 27, 1969, now abandoned.
Although overall colored effects as described above can be quite pleasing to the consumer, one of the most attractive and effective uses of color is a speckled effect which can be achieved by incorporating a minor proportion of particles which are large enough to be readily discernible with the naked eye into a composition of contrasting color. By uniformly dispersing such colored particles, a product having numerous, discrete, well-defined centers of contrasting color or colors randomly but uniformly distributed therethrough, i.e., a speckled product, is attained which presents a striking and highly distinctive appearance. While speckled toothpastes have long been known, the speckling is achieved by such substances as gold leaf and charcoal which are not really satisfactory from an aesthetic or economic standpoint. Thus, while the concept of speckling a toothpaste is old per se, no really effective means for executing this concept has been provided in the prior art.
The main requirements of such a speckle is that it be of sufficient size to be discernible as such; that it maintain its integrity and distinctness in the toothpaste base until the product is used; and that it be sufficiently frangible to break up into small particles in use. Thus, it must not leach, i.e., bleed, and color the entire dentifrice. Since the dyes certified for use in dentifrice products by the U.S. Food and Drug Administration are all water-soluble and toothpastes generally contain sufficient quantities of water to cause the dyes to leach and color the entire product, it has not been possible to prepare speckles which are colorfast yet sufficiently frangible to disintegrate in use so that they are not detectable in the mouth. Solid particles of the size required to produce the speckled effect generally produce an unpleasant gritty "berry seed" sensation in use, and actually become lodged between the teeth unless they break up into smaller particles when brushed upon the teeth.